(1) Field of the Invention
The present invention relates to means for and methods of testing for leakage flaws and weak spots of products capable of inflation such as surgical gloves.
(2) Description of the Prior Art
It is well known that in any manufacturing process that in order to maintain a reputation for quality in the eyes of consumers that it is necessary to exercise stringent quality control. This is of particular importance when manufacturing inflatable products as the same require only a minute flaw in order for them to be defective. This is especially the case with surgical gloves because with any flaw that can lead to an aperture or opening no matter how small there is a very considerable risk of infection to the patient.
Currently it is standard to test the integrity of inflatable products and in particular surgical gloves in one of several ways. The most common method is the inflation of the product and the use of visual examination for pinholes and weaknesses. The difficulty with this technique however, which uses only a low inflation pressure e.g. 1-2 lbs per inch.sup.2, is that even when for example a surgical glove is blown to a large size the fingers are not inflated and hence remain suspect for holes. Generally these are difficult to detect unless a great deal more time is spent by the tester, i.e. the tester waits for several minutes for the glove to deflate. The other difficulty that arises from the reliance upon visual examination of an inflated glove is that the tester must decide whether or not a weakness is passable or not. When this method is utilised it is often found that when quality is stressed the testers would rather play safe and destroy a glove on the detected weakness (e.g. by applying finger pressure thereto) rather than be reprimanded for the passing of sub-standard gloves thus leading to a high rate of spoilage while at the same time providing only marginal tests on the fingers. Other testing methods employ the use of liquids which even in the absence of pressure can provide a ready indication of a leakage. It is possible also to test using a liquid by applying an electric current to the liquid within the glove and detecting any current passage increase through the glove when the glove is in a second liquid. Such liquid using techniques however are slow and messy and preclude the use of a lubricant dust on the inside face of the gloves unless the same is to be applied afterwards thereby meaning that the testing of the glove occurs not only prior to packaging and sterilisation but also prior to dusting thereby reducing the reliability of the quality control.
U.S. Pat. No. 3,315,519 to W. C. Ferguson discloses a method of testing surgical gloves which utilises gas pressurisation while the glove is confined or constrained. The apparatus disclosed in that specification took no steps to minimise anomalous results that can arise through stress relaxation or creep of the latex rubber from which a surgical glove is formed. Moreover, the apparatus and method disclosed gave rise to a lengthy testing cycle or high inaccuracies owing to the pressure measurement technique and also the fact that steps were not taken to ensure the fingers of the surgical glove were not in contact.
Other testing methods used by manufacturers vary from batch testing to visual checking of deflated gloves over strong light. These techniques however do not provide a high degree of accuracy and hence in the art of manufacture of inflatable products such as balloons gloves etc there is a belief that a high degree of accuracy during other than batch tests is unobtainable without introducing prolonged testing procedures.